eudev/man/systemd-journald.service.xml
2012-06-17 00:03:12 +02:00

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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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<refentry id="systemd-journald.service">
<refentryinfo>
<title>systemd-journald</title>
<productname>systemd</productname>
<authorgroup>
<author>
<contrib>Developer</contrib>
<firstname>Lennart</firstname>
<surname>Poettering</surname>
<email>lennart@poettering.net</email>
</author>
</authorgroup>
</refentryinfo>
<refmeta>
<refentrytitle>systemd-journald</refentrytitle>
<manvolnum>8</manvolnum>
</refmeta>
<refnamediv>
<refname>systemd-journald.service</refname>
<refname>systemd-journald</refname>
<refpurpose>systemd Journal Service</refpurpose>
</refnamediv>
<refsynopsisdiv>
<para><filename>systemd-journald.service</filename></para>
<para><filename>/usr/lib/systemd/systemd-journald</filename></para>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><filename>systemd-journald</filename> is a
system service that collects and stores logging
data. It creates and maintains structured, indexed
journals based on logging information that is received
from the kernel, from user processes via the libc
<citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
call, from STDOUT/STDERR of system services or via its
native API. It will implicitly collect numerous meta
data fields for each log messages in a secure and
unfakeable way. See
<citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>
for more information about the collected meta data.
</para>
<para>Log data collected by the journal is primarily
text based but can also include binary data where
necessary. All objects stored in the journal can be up
to 2^64-1 bytes in size.</para>
<para>By default the journal stores log data in
<filename>/run/log/journal/</filename>. Since
<filename>/run/</filename> is volatile log data is
lost at reboot. To make the data persistent it
is sufficient to create
<filename>/var/log/journal/</filename> where
<filename>systemd-journald</filename> will then store
the data.</para>
<para><filename>systemd-journald</filename> will
forward all received log messages to the AF_UNIX
SOCK_DGRAM socket
<filename>/run/systemd/journal/syslog</filename> (if it exists) which
may be used by UNIX syslog daemons to process the data
further.</para>
<para>See
<citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
for information about the configuration of this
service.</para>
</refsect1>
<refsect1>
<title>Signals</title>
<variablelist>
<varlistentry>
<term>SIGUSR1</term>
<listitem><para>Request that journal
data from <filename>/run/</filename>
is flushed to
<filename>/var/</filename> in order to
make it persistent (if this is
enabled). This may be used after
<filename>/var/</filename> is mounted,
but is generally not required since
the first journal write when
<filename>/var/</filename> becomes
writable triggers the flushing
anyway.</para></listitem>
</varlistentry>
<varlistentry>
<term>SIGUSR2</term>
<listitem><para>Request immediate
rotation of the journal
files.</para></listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>